 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.internal.variables;

 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.core.variables.IDynamicVariable;
 import org.eclipse.core.variables.IDynamicVariableResolver;
 import org.eclipse.core.variables.VariablesPlugin;
 import org.eclipse.osgi.util.NLS;

 /**
  * Dynamic variable
  */
 public class DynamicVariable extends StringVariable implements IDynamicVariable {
     
     /**
      * Resolver, or <code>null</code> until needed
      */
     private IDynamicVariableResolver fResolver;

     /* (non-Javadoc)
      * @see org.eclipse.debug.internal.core.stringsubstitution.IContextVariable#getValue(java.lang.String)
      */
     public String getValue(String argument) throws CoreException {
         if (!supportsArgument()) {
             // check for an argument - not supported
 if (argument != null && argument.length() > 0) {
                 throw new CoreException(new Status(IStatus.ERROR, VariablesPlugin.getUniqueIdentifier(), VariablesPlugin.INTERNAL_ERROR, NLS.bind(VariablesMessages.DynamicVariable_0, new String []{argument, getName()}), null));
             }
         }
         if (fResolver == null) {
             String name = getConfigurationElement().getAttribute("resolver"); //$NON-NLS-1$
 if (name == null) {
                 throw new CoreException(new Status(IStatus.ERROR, VariablesPlugin.getUniqueIdentifier(), VariablesPlugin.INTERNAL_ERROR, NLS.bind("Contributed context variable {0} must specify a resolver.",new String []{getName()}), null)); //$NON-NLS-1$
 }
             Object object = getConfigurationElement().createExecutableExtension("resolver"); //$NON-NLS-1$
 if (object instanceof IDynamicVariableResolver) {
                 fResolver = (IDynamicVariableResolver)object;
             } else {
                 throw new CoreException(new Status(IStatus.ERROR, VariablesPlugin.getUniqueIdentifier(), VariablesPlugin.INTERNAL_ERROR, NLS.bind("Contributed context variable resolver for {0} must be an instance of IContextVariableResolver.",new String []{getName()}), null)); //$NON-NLS-1$
 }
         }
         return fResolver.resolveValue(this, argument);
     }

     /**
      * Constructs a new context variable.
      *
      * @param name variable name
      * @param description variable description or <code>null</code>
      * @param configurationElement configuration element
      */
     public DynamicVariable(String name, String description, IConfigurationElement configurationElement) {
         super(name, description, configurationElement);
     }

     /* (non-Javadoc)
      * @see org.eclipse.core.variables.IDynamicVariable#supportsArgument()
      */
     public boolean supportsArgument() {
         String arg = getConfigurationElement().getAttribute("supportsArgument"); //$NON-NLS-1$
 return arg == null || Boolean.valueOf(arg).booleanValue();
     }
     
 }

